There is a fit girl i like and when we r in tha gym she tries to look up my shorts what do i do?

i was on a board that you lie on and do sit ups on but when you lie down properly your upside down and this girls was standin infront of me and she kept lookin at me shorts so i said are u lookin for somethin and sh said ye...umm.....i mean no y do u ask and i said you keep lookin and my pants so she said naa i dont then went bright red